The interaction of IL-6, a protein originally identified as a B cell differentiation factor (Hirano et al., 1985, Proc. Natl. Acad. Sci. USA, 82: 5490-4; EP 0257406), with IL-6R (Yamasaki et al., 1988, Science, 241: 825-8; EP 0325474) results in the formation of the IL-6/IL-6R complex. This complex binds to gp130 (Taga et al., 1989, Cell, 58: 573-81; EP 0411946), a membrane protein on a target cell, which transmits various physiological actions of IL-6. IL-6 is currently known to be involved in—amongst others—the regulation of the immune response, hematopoiesis, the acute phase response, bone metabolism, angiogenesis, and inflammation. Deregulation of IL-6 production is implicated in the pathology of several autoimmune and chronic inflammatory proliferative disease processes (Ishihara and Hirano, 2002, Biochim. Biophys. Acta, 1592: 281-96). As a consequence, inhibitors of IL-6 induced signaling have attracted much attention in the past (Hirano et al., 1990, Immunol. Today, 11: 443-9). Polypeptides specifically binding to IL-6 (Klein et al., 1991, Blood, 78: 1198-204; EP 0312996), IL-6R (EP 0409607) or gp130 (Saito et al., 1993, J. Immunol. Methods, 163: 217-223; EP 0572118) proved to exhibit an efficient inhibitory effect on IL-6 functioning.
IL-6 overproduction and signalling (and in particular so-called trans-signalling) are involved in various diseases and disorders, such as sepsis (Starnes et al., 1999, J. Immunol., 148: 1968) and various forms of cancer such as multiple myeloma disease (MM), renal cell carcinoma (RCC), plasma cell leukaemia (Klein et al., 1991), lymphoma, B-lymphoproliferative disorder (BLPD) and prostate cancer. Non-limiting examples of other diseases caused by excessive IL-6 production or signalling include bone resorption (osteoporosis) (Roodman et al., 1992, J. Bone Miner. Res., 7: 475-8; Jilka et al., 1992, Science, 257: 88-91), cachexia (Strassman et al., 1992, J. Clin. Invest. 89: 1681-1684), psoriasis, mesangial proliferative glomerulonephritis, Kaposi's sarcoma, AIDS-related lymphoma (Emilie et al., 1994, Int. J. Immunopharmacol. 16: 391-6), inflammatory diseases and disorder such as rheumatoid arthritis, systemic onset juvenile idiopathic arthritis, hypergammaglobulinemia (Grau et al., 1990, J. Exp. Med. 172: 1505-8); Crohn's disease, ulcerative colitis, systemic lupus erythematosus (SLE), multiple sclerosis, Castleman's disease, IgM gammopathy, cardiac myxoma, asthma (in particular allergic asthma) and autoimmune insulin-dependent diabetes mellitus (Campbell et al., 1991, J. Clin. Invest. 87: 739-742). Other IL-6 related disorders will be clear to the skilled person.
As can for example be seen from the references above, the prior art describes antibodies and antibody fragments directed against human IL-6, against human IL-6R and against human gp130 protein for the prevention and treatment of IL-6 relates disorders. Examples are Tocilizumab (see Woo et al., 2005, Arthritis Res. Ther. 7: 1281-8; Nishimoto et al., 2005, Blood 106: 2627-32; Ito et al., 2004, Gastroenterology, 126: 989-96; Choy et al., 2002, Arthritis Rheum. 46: 3143-50), BE8 (see Bataille et al., 1995, Blood 86: 685-91; Emilie et al., 1994, Blood 84: 2472-9; Beck et al., 1994, N. Engl. J. Med. 330: 602-5; Wendling et al., 1993, J. Rheumatol. 20: 259-62) and CNTO-328 of Centocor (see Journal of Clinical Oncology, 2004, 22/14S: 2560; Journal of Clinical Oncology, 2004, 22/14S: 2608; Int. J. Cancer, 2004, 111:592-5). Another active principle known in the art for the prevention and treatment of IL-6 related disorders is an Fc fusion of soluble gp130 (see Becker et al. 2004, Immunity, 21: 491-501; Doganci et al., 2005, J. Clin. Invest. 115: 313-25; Nowell et al., 2003, J. Immunol. 171: 3202-9; Atreya et al., 2000, Nat. Med. 6: 583-8). Amino acid sequences and Nanobodies directed against IL-6R and polypeptides comprising the same are described in WO 08/020079.